Industrial floor cleaning systems generally provide for the management of heat, vacuum, pressure, fresh and gray water, chemicals, and power to achieve the goal of efficient, thorough cleaning of different substrates, usually carpets but also hard flooring, linoleum and other substrates, in both residential and commercial establishments. Professional substrate cleaning systems are also utilized in the restoration industry for water extraction.
Of the many industrial substrate cleaning systems available, a major segment are self-contained having an own power plant, heat source, vacuum source, chemical delivery system, and water dispersion and extraction capabilities. These are commonly referred to as “slide-in” systems and install permanently in cargo vans, trailers and other commercial vehicles, but can also be mounted on portable, wheeled carts. Slide-in systems comprise a series of components designed and integrated into a package with an overall goal of performance, economy, reliability, safety, useful life, serviceability, and sized to fit in various commercial vehicles.
FIG. 1 schematically illustrates a state-of-the-art industrial slide-in substrate cleaning system 1 (shown without scale) for carpets, hard flooring, linoleum and other substrates, one well-known example of which is the self-contained, gas-powered, truck-mounted model CTS-450 that is commercially available from Hydramaster Corporation, Mukilteo, Wash.
FIG. 1 illustrates the components of a conventional slide-in carpet cleaner system 1 structured around a frame or structural platform 2 onto which the majority of the components are mounted. The slide-in 1 includes a drive system 3 mounted on the platform 2 and having a power plant 4 coupled to receive fuel from an appropriate supply, a vacuum blower 5 that is the vacuum source for removing soiled water from the cleaned substrate, either carpet or other flooring, and an interface assembly 6 for transmitting power from the power plant to the vacuum blower. A standard truck battery 7 is provided as a source of electric energy for starting the engine. An intake hose 8 is coupled to a source of fresh water, and a water pump or air compressor 9 driven by the power plant via V-belt (shown), direct drive, or otherwise for pressurizing the fresh water. One or more heat exchangers and associated plumbing 10 is coupled for receiving the pressurized fresh water and heating it. A recovery tank 11 is provided wherein gray water is stored after removal from the cleaned surface. A high pressure solution hose 12 is provided for delivering pressurized, hot water/chemical solution from the machine via a wand or power head to the substrate to be cleaned, usually a carpet or hard flooring, and a chemical container 13 or other chemical system is coupled for delivering a stream of cleaning chemical into hot water as it enters the high-pressure solution hose. A wand or power head 14 is coupled to the high pressure solution hose 12 for receiving and dispersing the pressurized hot water/chemical cleaning solution to the carpet. The wand or power head 14 is the only “portable” part of truck-mount slide-in professional carpet cleaning systems in that it is removed from the vehicle and carried to the carpet or other substrate to be cleaned, and it is the only equipment that makes physical contact with the carpet to be cleaned. A vacuum hose 15 is coupled to the wand or power head 14 for recovering the soiled water-based chemical cleaning solution from the cleaned surface via the wand or power head and delivering it to the recovery tank.
The slide-in system 1 operates by delivering fresh water to an inlet to the system, utilizing either a standard garden hose or a fresh-water container. The system adds energy to the fresh water, i.e., pressurizes it, by means of the pump or air compressor 9. The fresh water is pushed throughout the heat exchanger apparatus and associated plumbing 10 using pressure provided by either the pump or air compressor. The heat exchangers gain their heat by thermal energy rejected from the power plant 4, e.g., from hot exhaust gasses, coolant water used on certain engines, or another known means. On demand from the wand or power head 14, the heated fresh water is mixed with chemicals as the hot water is exiting the machine and entering the high-pressure hose 12. The hot water travels typically, but not limited to, between 50 feet to 300 feet to the wand or power head 14. The operator delivers the hot solution via the wand or power head 14 to the carpet or other surface to be cleaned and almost immediately extracts it along with soil that has been emulsified by thermal energy or dissolved and divided by chemical energy. The extracted, soiled water is drawn via the vacuum hose 15 into the recovery tank 11 for eventual disposal as gray water.
FIG. 2 illustrates the drive system 3 of an industrial carpet cleaner as having several components. Three crucial parts of this drive system 3 are a power plant 4, such as an engine, a vacuum blower 5, and an interface assembly 6 that transmits power from the power plant 4 to the vacuum blower 5. The power plant 4 is, for example, any steam, electric or internal combustion motor, such as a gasoline, diesel, alcohol, propane, or otherwise fueled internal combustion engine.
As FIG. 2 illustrates, the power plant or engine 4 and vacuum blower 5 of a current state-of-the-art industrial carpet cleaner drive system 3 are independently metal-to-metal hard-mounted on a sturdy metal support frame 2 either directly (shown for vacuum blower 5) using multiple mechanical fasteners 16, e.g., bolt or screws, or using sturdy metal brackets 17 (shown for power plant 4) and fasteners 16. The-metal support frame 2 is used for mounting in a van, truck or another suitable vehicle for portability, as illustrated in FIG. 1. Optionally, the support frame is wheeled for portability independent of the vehicle. The professional carpet cleaning industry currently uses one of two different interface assemblies 6 for transmitting power from the power plant 4 to the vacuum blower 5: either a belt drive system or a coupling drive system (shown).
The belt drive system (not shown) transmits power through pulleys and belts, which suffer inherent problems of wear and breakage. Belt slippage and loss of tension result in lost power and efficiency. Belt drives typically fail catastrophically, thus causing the end-user down-time. Also, fast moving belt drives are safety hazards requiring installation of protective guards. Since some protective guards can be removed by an end-user, safety hazards cannot be completely eliminated.
The coupling drive system transmits power from the power plant output or drive shaft 18 directly to the vacuum blower input or drive shaft 19 through one of several known coupling means.
A problem common to both belt and coupling drive systems is misalignment of the drive components. In belt drives, pulleys attached to the engine and vacuum blower drive shafts require strict alignment to ensure proper operation of the belts and maximum efficiency. In coupling drives, even slight lateral and angular misalignments of the respective power output and input drive shafts 18, 19 result in vibration, gear chatter, high wear rates, and ultimately catastrophic failure.
FIGS. 3A and 3B illustrate a known C-Face coupling 20 useful as the interface assembly 6 for forming a direct drive joint between the power plant output drive shaft 18 and the vacuum blower input drive shaft 19. FIG. 3A is perspective view of the C-Face coupling 20 showing the power plant output drive shaft 18 and the vacuum blower input drive shaft 19 joined and rotationally fixed to respective inwardly facing hubs 22, 24. The two hubs 22, 24 are both joined and rotationally fixed to a center section 26 of the C-Face coupling 20 by multiple fasteners 28 between respective cooperating flanges 30, 32 and 34, 36. Torque generated by the power plant 4 and output through drive shaft 18 is thus transmitted through the C-Face coupling 20 and input to the vacuum blower 5 through its drive shaft 19.
FIG. 3B is a cross-section through the C-Face coupling 20 illustrated in FIG. 3A and shows elongated portions 38, 40 of the respective hubs 22, 24 having the respective power plant and vacuum blower drive shafts 18, 19 extending therethrough. The elongated portions hub portions 38, 40 are shown extending inside a bore through the center section 26. The C-Face coupling 20 is alternatively expanded as necessary by reversing either of the hubs 22, 24 such that its respective elongated portion 38, 40 is outside the center section 26.
Multiple clearance holes 42 through the wall of the center section 26 permit access to install multiple pins or set screws (shown) 44 through the walls of the elongated hub portions 38, 40 for clamping and rotationally fixing the output and input drive shafts 18, 19 relative to the respective hubs 22, 24.
When operated with the independent mounting of the drive system components currently used in professional carpet cleaners, the traditional belt and coupling drive systems must rely on the metal frame 2 to provide and maintain the precise alignment required of the vacuum blower 5 relative to the power plant 4. Given the difficulty of achieving and maintaining such precise vacuum blower-to-power plant alignment, the metal frame 2 is necessarily a heavy and rigid structure to absorb and minimize significant vibrations resulting from imprecise alignment.
Furthermore, when under load, e.g., when the carpet wand 14 is engaged firmly to the carpet providing for maximum vacuum seal, the vacuum blower 5 responsively produces an asymmetric radial shock pulse along its driven shaft 19. These shock pulses produce a cyclic eccentric load that, in an improperly aligned C-Face drive system exacerbates any misalignment and further increases wear, thereby decreasing the coupling's useful life.
One attempt to reduce the effects of imprecise alignment involves inserting elastomeric vibration dampeners at the interface between the power plant output and the vacuum blower input. For example, neoprene pads 46 are provided between the hub and center section flanges 30, 32 and 34, 36 of the C-Face coupling 20 to dampen vibrations due to slight lateral and angular misalignments of the power plant and vacuum blower drive shafts 18, 19. Alternatively, neoprene plugs or bushings 48 are provided at each of the fasteners 28 joining the flanges 30, 32 and 34, 36. Unfortunately, the C-Face coupling is known to lose efficiency through vibration of the neoprene pads 46 and bushings 48, which also absorb the torque impact output at the output drive shaft 18.
FIGS. 4A, 4B and 4C illustrate other means of reducing the effects of imprecise alignment by embodying the interface assembly 6 as a flexible coupling. FIG. 4A is a perspective view illustrating a known flexible coupling, the “Waldron” coupling, 50 that uses two hubs 52, 54 structured for positive mounting on the respective engine and blower shaft 18, 19. External splines 56, 58 on respective the hubs are engaged by generated internal splines 60, 62 cut on a bore of a casing or sleeve 64. The external or internal splines 56, 58 or 60, 62 may be formed of an elastomer, such as neoprene or nylon, for absorbing vibrations and impacts due to fluctuations in shaft torque or angular speed. Such flexible couplings, however, may lose some efficiency through vibration of the elastomer when the external or internal splines are formed of neoprene or nylon to reduce the effects of imprecise alignment.
FIG. 4B is a partial cut-away side view and FIG. 4C is an end-on section view that together illustrate the interface assembly 6 embodied as a known “Fast” flexible coupling 80 that consists of two hubs 82, 84 each keyed to its respective engine and blower shaft 18, 19. Each hub 82, 84 has generated splines 86 cut at a distance from the end of the respective power plant and vacuum blower drive shaft 18, 19. A casing or sleeve 88 is split transversely and is fitted to surround the hubs 82, 84 where it is bolted by means of flanges 90, 92. Each half of the sleeve has generated internal splines 94 cut on its bore at the end opposite to the flange. The internal splines 94 permit a definite error of alignment between the two shafts.
Other known flexible couplings for transmitting power from the engine to the vacuum blower include the chain coupling that uses either silent chain or standard roller chain with the mating sprockets; and Steelflex couplings having two grooved steel hubs keyed to the respective shafts, connection between the two halves being secured by a specially tempered alloy-steel member called the “grid.”
In a known rubber flexible coupling torque is transmitted through a comparatively soft rubber section intermediate between hubs on the respective shafts and acting in shear.
Universal joints are commonly used to connect shafts with larger values of misalignment than can be tolerated by the other types of flexible couplings. The known Bendix-Weiss “rolling-ball” universal joint provides constant angular velocity with torque being transmitted between two yokes through a set of four balls such that the centers of all four balls lie in a plane which bisects the angle between the shafts. Other variations of constant velocity universal joints are found in the known Rzeppa, Tracta, and double Cardan types.
Fluid couplings are also known having no mechanical connection between the two shafts, power being transmitted by kinetic energy in the operating fluid, whereby slight lateral and angular misalignments can be tolerated.
Clutches are known couplings that permit the disengagement of the coupled shafts during rotation. Positive clutches, such as the jaw and spiral clutches, transmit torque without slip. Friction clutches reduce coupling shock by slipping during engagement, and also serve as safety devices by slipping when the torque exceeds their maximum rating.
All of the described flexible couplings, as well as other known flexible couplings, are designed to connect shafts which may be slightly misaligned either laterally or angularly. A secondary benefit is the absorption of vibration and impacts due to fluctuations in shaft torque or angular speed. Flexible couplings however suffer a loss in efficiency with increasing angle between the connected shafts. Flexible couplings using fluid, clutch, or elastomeric interfaces for absorbing vibrations and impacts suffer efficiency losses through vibration of the damping medium, while elastomeric interfaces, such as neoprene or nylon, are additionally subject to unacceptably high wear rates.